1. Field of the Invention
The present invention relates to seat reclining devices for a vehicle seat. More particularly, the present invention relates to seat reclining devices for a vehicle seat that comprise a seat reclining mechanism disposed on each side of the vehicle seat.
2. Description of the Related Art
As shown in FIG. 9, a known seat reclining device for a vehicle seat (not shown) includes a first (outer) seat reclining mechanism 70 and a second (inner) seat reclining mechanism 74. These two seat reclining mechanisms 70 and 74 are utilized in order to provide sufficient support strength between a seat back and a seat cushion (not shown) of the vehicle seat. As will be recognized, the outer and inner seat reclining mechanisms 70 and 74 are respectively disposed on the left and right sides of the vehicle seat.
The outer seat reclining mechanism 70 includes a pair of opposing disk-like housings, i.e., a first housing 12 and a second housing 14. The first housing 12 is affixed to a cushion frame 30 that supports the vehicle seat cushion. The second housing 14 is affixed to a seat back frame 32 that supports the vehicle seat back. The first and second housings 12 and 14 are circumferentially connected by a fastener or clip ring 16 so that the first housing 12 can move or rotate relative to the second housing 14 around a rotational axis L. Further, the rotational axis L corresponds to a common centerline of the first and second housings 12 and 14.
The outer seat reclining mechanism 70 also includes a rotational rod or shaft 72 that extends along the rotational axis L through the cushion frame 30 and the seat back frame 32, as well as through the first and second housings 12 and 14. As shown in FIG. 11(A), the first rotational shaft 72 includes a first (inner) extended portion 72a having a rectangular shape in cross section and an outer diagonal dimension P1. Also, the first rotational shaft 72 includes a second (outer) extended portion (manipulating portion) 28, which portion is typically connected to a seat operation handle or lever (not shown).
As best shown in FIGS. 10(A) and 10(B), the outer seat reclining mechanism 70 further includes a locking means that can prevent the first housing 12 from rotating relative to the second housing 14, and thereby lock the seat reclining mechanism 70. The locking means essentially consists of a hinge cam 20, a slide member 24 and a pair of pawls 26 that are received within the housings 12 and 14. The hinge cam 20 is secured to or integrally formed with the first rotational shaft 72, so as to rotate with the first rotational shaft 72. The slide member 24 is laterally movably or slidably attached to the first housing 12. The slide member 24 includes a specially shaped central bore 24a that receives the hinge cam 20. The central bore 24a partially engages the hinge cam 20, so that the slide member 24 can laterally slide or move in the direction shown by arrow D1 when the first rotational shaft 72 rotates. As will be recognized, the slide member 24 is configured in order to reliably prevent the slide member 24 from rotating relative to the first housing 12.
In addition, the pawls 26 are vertically movably or slidably attached to the first housing 12. One pawl 26 is disposed on each side of the slide member 24 and the pair of pawls 26 is configured to engage the slide member 24. Thus, the pawls 26 can vertically slide or shift in the direction shown by arrow D2. As will be recognized, the pawls 26 are configured in order to reliably prevent the pawls 26 from rotating relative to the first housing 12.
Further, as shown in FIGS. 10(A) and 10(B), the second housing plate 14 has an inner circular surface 14a. A pair of concave toothed portions 15 circumferentially extend over two separate portions of the inner circular surface 14a. Each of the pawls 26 has a curved outer surface 26a. A corresponding convex toothed portion 27 is provided on each pawl 26 for releasably engaging the respective concave toothed portions 15.
In addition, as shown in FIG. 9, a biasing (spiral) spring 22 is disposed within the first housing 12. The spiral spring 22 urges (biases) the first rotational shaft 72 in the direction shown by arrow D3 (counterclockwise). As a result, the first rotational shaft 72 is normally retained in a locked position, which position corresponds to the position shown in FIG. 10(A). When the first rotational shaft 72 is retained in the locked position, the slide member 24 is positioned at the leftmost position. When the slide member 24 is retained in this position, the slide member 24 pushes or urges the respective pawls 26 in opposite outward directions so that the respective convex toothed portions 27 engage the concave toothed portions 15. In this state, the first housing 12 is prevented from rotating relative to the second housing 14, thereby locking the outer seat reclining mechanism 70. As a result, the seat back frame 32 is locked in position relative to the cushion frame 30 and thus, the seat back is locked relative to the seat cushion.
When the first rotational shaft 72 is rotated in the direction shown by arrow D4 (clockwise) against the urging force of the spiral spring 22, the first rotational shaft 72 rotates toward an unlocked position, which position corresponds to the position shown in FIG. 10(B). When the first rotational shaft 72 is rotated to the unlocked position, the slide member 24 is positioned in the rightmost position. When the slide member 24 is retained in this position, the slide member 24 moves or pushes the respective pawls 26 in the inward direction, so that the convex tooth portions 27 disengage from the concave toothed portions 15. In this state, the first housing 12 can freely rotate relative to the second housing 14, thereby unlocking the outer seat reclining mechanism 70. As a result, the seat back frame 32 can freely rotate or pivot relative to the cushion frame 30, such that the seat back can be tilted relative to the seat cushion.
With the exception of one aspect, the inner seat reclining mechanism 74 has substantially the same construction as the outer seat reclining mechanism 70. The difference is that the inner seat reclining mechanism 74, which includes a rotational rod or shaft 76 that has an inner extended portion 76a similar to the inner extended portion 72a, does not include an outer extended portion or manipulation portion 28. Further description of the inner seat reclining mechanism 74 can be omitted, because the remaining constructions are the same.
In the above-described known seat reclining device, the first rotational shaft 72 is interconnected with the second rotational shaft 76 via a connector sleeve 78. The connector sleeve 78 has a rectangular shape in cross section and this rectangular shape corresponds to the rectangular shape of the inner extended portion 72a of the first rotational shaft 72. As shown in FIG. 11(A), the connector sleeve 78 has an inner diagonal dimension P2 that is larger than the outer diagonal dimension P1 of the inner extended portion 72a. The inner extended portion 72a is inserted into the connector sleeve 78, to thereby define a loose nesting coupling 80 between the inner extended portion 72a and the connector sleeve 78. On the other hand, the inner extended portion 76a of the second rotational shaft 76 is inserted into and welded to the connector sleeve 78, thereby securely or fixedly connecting the second rotational shaft 76 to the connector sleeve 78. As shown in FIG. 9, a portion of the periphery of the connector sleeve 78 is removed in order to define a removed portion 79 that is welded to the outer surface of the inner extended portion 76a. 
Thus, the first rotational shaft 72 is rotationally and synchronously coupled to the second rotational shaft 76, such rotation of the first rotational shaft 72 will be transmitted to the second rotational shaft 76. Therefore, when the seat operation lever is pivoted or rotated, thereby rotating the first rotational shaft 72, the second rotational shaft 76 is also driven or rotated. Consequently, both seat reclining mechanisms 70 and 74 can be simultaneously or synchronously unlocked by simply operating the seat operation lever that is attached to the first rotational shaft 72. As a result, the seat back frame 32 can be rotated relative to the cushion frame 30 by simply operating the seat operation lever, thereby enabling the seat back to be tilted relative to the seat cushion.
As described above, because the inner diagonal dimension P2 of the connector sleeve 78 is greater than the outer diagonal dimension P1 of the inner extended portion 72a, a clearance S is defined between the inner extended portion 72a and the connector sleeve 78 (FIG. 11(A)). The clearance S allows the first rotational shaft 72 to idly rotate with respect to the connector sleeve 78 by a small degree. As a result, the first rotational shaft 72 can be freely and oppositely rotated relative to the second rotational shaft 76, which is integrally formed with the connector sleeve 78.
By attaching the outer and inner reclining mechanisms 70 and 74 to the seat cushion and the seat back, these parts are interconnected and form a reclinable vehicle seat. The vehicle seat thus assembled is then mounted within a vehicle body (not shown) in a vehicle assembly line. However, the vehicle seat may be twisted or deformed while being mounted within the vehicle body. Such twisting may result from inaccurate positioning due to dimensional errors between a seat attachment (not shown) of the seat and a seat mount (not shown) of the vehicle body. If the vehicle seat is twisted while being mounted to the vehicle body, the outer seat reclining mechanism 70 will be rotationally deviated from the inner seat reclining mechanism 74. In other words, if the vehicle seat is twisted while being mounted within the vehicle body, the reclining mechanisms 70 and 74 will be rotated in opposite directions relative to each other. As a result, the first rotational shaft 72 also will be rotated in an opposite direction relative to the second rotational shaft 76.
As described above, because the clearance S is formed between the inner extended portion 72a and the connector sleeve 78, the first rotational shaft 72 can freely rotate without interfering with the second rotational shaft 76. Thus, even if the outer reclining mechanism 70 is rotationally deviated from the inner reclining mechanism 74, the relative deviation of the outer and inner reclining mechanisms 70 and 74 can be effectively compensated. As a result, even if the vehicle seat is twisted while being mounted, such twisting of the seat may not have any adverse effect on the function of the seat reclining mechanisms 70 and 74.
As will be recognized, the outer and inner reclining mechanisms 70 and 74 must be attached to the vehicle seat such that the first rotational shaft 72 is conformably or appropriately positioned relative to the connector sleeve 78, as shown in FIG. 11(A). In other words, when the outer and inner reclining mechanisms 70 and 74 are attached to the vehicle seat, the first rotational shaft 72 must be positioned in such a manner that it does not contact the connector sleeve 78. In this case, the clearance S will extend continuously around the first rotational shaft 78, so that the first rotational shaft 72 does not contact the connector sleeve 78. If the first rotational shaft 72 is thus positioned relative to the connector sleeve 78, the first rotational shaft 72 can freely rotate in either direction (clockwise and counterclockwise) with respect to the connector sleeve 78. Therefore, even if the outer reclining mechanism 70 is somewhat rotationally deviated in either direction with respect to the inner reclining mechanism 74 while the vehicle seat is being mounted within the vehicle body, such relative deviation of the outer and inner reclining mechanisms 70 and 74 can be effectively compensated.
However, the outer and inner reclining mechanisms 70 and 74 also may be attached to the vehicle seat such that the first rotational shaft 72 is non-conformably or inappropriately positioned relative to the connector sleeve 78, as shown by a solid line in FIG. 11(B). In other words, when the outer and inner reclining mechanisms 70 and 74 are being attached to the vehicle seat, the first rotational shaft 72 may be positioned in such a manner that the first rotational shaft contacts the connector sleeve 78. In this case, the clearance S will not be continuous.
If the first rotational shaft 72 is thus positioned relative to the connector sleeve 78, the first rotational shaft 72 can freely rotate in only one direction (i.e., clockwise) with respect to the connector sleeve 78. Therefore, if the outer reclining mechanism 70 is rotationally deviated clockwise with respect to the inner reclining mechanism 74 when the vehicle seat is being mounted to the vehicle body, such relative deviation of the outer and inner reclining mechanisms 70 and 74 can be reliably compensated. However, if the outer reclining mechanism 70 is rotationally deviated in the opposite direction (i.e., counterclockwise) with respect to the inner reclining mechanism 74 when the vehicle seat is being mounted within the vehicle body, such relative deviation of the outer and inner reclining mechanisms 70 and 74 can not be compensated. In this case, the first rotational shaft 72 is prevented from freely rotating in the counterclockwise direction with respect to the connector sleeve 78.
That is, if the outer reclining mechanism 70 is rotationally deviated counterclockwise with respect to the inner reclining mechanism 74, the first rotational shaft 72 may generate a counterclockwise rotational force within the connector sleeve 78, so as to force or bias the connector sleeve 78 in the counterclockwise direction. However, the connector sleeve 78 can not rotate in the counterclockwise direction, because the second rotational shaft 76, which is integrally formed with the connector sleeve 78, is prevented from excessively rotating past the locked position. As noted above, the locked position of the first rotational shaft 72 is shown in FIG. 10(A). As a result, the first rotational shaft 72 is forced or urged to reversibly rotate (i.e., rotate in the clockwise direction) against the biasing force of the spiral spring 22. Thus, the first rotational shaft 72 will rotate from the locked position as shown in FIG. 10(A) toward the unlocked position as shown in FIG. 10(B). Such reverse rotation of the first rotational shaft 72 may cause an incomplete locking or half locking of the reclining mechanism 70.
Furthermore, as shown by a broken line in FIG. 11(B), the outer and inner reclining mechanisms 70 and 74 may be attached to the vehicle seat such that the first rotational shaft 72 is non-conformably positioned relative to the connector sleeve 78 in the opposite direction. If the first rotational shaft 72 is thus positioned relative the connector sleeve 78, the first rotational shaft 72 can freely rotate in only one direction (i.e., the counterclockwise direction) with respect to the connector sleeve 78. Therefore, if the outer seat reclining mechanism 70 is rotationally deviated in the counterclockwise direction with respect to the inner seat reclining mechanism 74 when the vehicle seat is being mounted within the vehicle body, such relative deviation of the outer and inner seat reclining mechanisms 70 and 74 can be reliably compensated. However, if the outer reclining mechanism 70 is rotationally deviated in the opposite direction (i.e., clockwise) with respect to the inner reclining mechanism 74 when the vehicle seat is being mounted within the vehicle body, such relative deviation of the outer and inner reclining mechanisms 70 and 74 can not be compensated. In this case, the first rotational shaft 72 is prevented from freely rotating in the clockwise direction with respect to the connector sleeve 78.
That is, if the outer seat reclining mechanism 70 is rotationally deviated in the clockwise direction with respect to the inner seat reclining mechanism 74, the first rotational shaft 72 may generate a clockwise rotational force within the connector sleeve 78, so as to force or bias the connector sleeve 78 in the clockwise direction. Therefore, the connector sleeve 78 is forced or urged to rotate in the clockwise direction against a biasing force of a spiral spring (not shown) disposed within the inner reclining mechanism 74. At this time, the first rotational shaft 72 can not rotate in the reverse (counterclockwise) direction, because the first rotational shaft 72 is prevented from excessively rotating past its locked position (FIG. 10(A)). As a result, the second rotational shaft 76, which is integrally formed with the connector sleeve 78, will rotate from its locked position toward its unlocked position. Such rotation of the second rotational shaft 76 may cause an incomplete locking or half locking of the reclining mechanisms 74.